This is definitely not PoE, just a hack on top of normal ethernet infrastructure. If you use one of these with a normal PoE switch you will fry whatever is connected on the other side, as it won't step down the voltage from 48V to 5V. Both sides need to be using this, but then real PoE is guaranteed to work even on 100m long cables, with this your 5V will end up being <4V with a 100m long cable and potentially useless.